The primary light-induced processes of phycocyanobilin were studied by means of transient-grating spectroscopy, whereby the excitation wavelength was varied over the spectral region of the ground-state absorption. On the basis of the results obtained, both the rate of the photoreaction in phycocyanobilin and the ratio of the decay of different excited-state species via two decay channels depend on the excitation wavelength. Furthermore, the formation of the photoreaction product is also dependent on the pump color. These data support a recently established model for the primary photoprocesses in phycocyanobilin. In addition, phycocyanobilin protonated at the basic pyrrolenine-type nitrogen atom was included in the transient absorption study. The decay behavior was found to be almost unchanged when compared with the unprotonated form, and this suggests that protonation of the tetrapyrrole ring structure has no effect on the overall photochemistry.